Catalyst system for polymerizing saturated,aliphatic aldehydes

ABSTRACT

A CATALYST SYSTEM FOR POLYMERIZING OR COPOLYMERIZING ALDEHYDES, COMPRISING A MIXTURE OF (1) DIALKYLZINC, (2) A CO-CATALYST, SUCH AS ALCOHOL, AMINE, OR WATER, AND (3) A STABLILIZING AGENT HAVING THE FORMULA   R1-N(-R2)-CO-N(-R3)-R4   WHEREIN EACH R REPRESENTS HYDROGEN, ALKYL, CYCLOALKYL, ARALKYL, OR ARYL RADICALS, AND WHEN R1, R2 AND R3=HYDROGEN, R4 CONTAINS AT LEAST THREE CARBON ATOMS.

United States Patent 3,579,480 CATALYST SYSTEM FOR POLYMERIZINGSATURATED, ALIPHATIC ALDEHYDES Henricus Gerardus Josef Overmars, Zeist,and Jan Gerrit Noltes, Utrecht, Netherlands, assignors to InternationallI??? Zinc Research Organization, Inc., New York, No Drawing. Filed June5, 1968, Ser. No. 734,577 Claims priority, application Netherlands, June20, 1967, 6708558 Int. Cl. C08g 1/06, 1/08 U.S. Cl. 260-67R 11 ClaimsABSTRACT OF THE DISCLOSURE A catalyst system for polymerizing orcopolymerizing aldehydes, comprising a mixture of (1) dialkylzinc, (2) aco-catalyst, such as alcohol, amine, or water, and '(3) a stabilizingagent having the formula R Rs wherein each R represents hydrogen, alkyl,cycloalkyl, aralkyl, or aryl radicals, and when R R and R =hydrogen, Rcontains at least three carbon atoms.

This invention relates to a catalyst system for polymerizing aldehydes,and more particularly to a catalyst system incorporating a stabilizingagent.

Aldehydes have been polymerized using dialkylzinc as a catalyst and withwater, alcohols, or amines as cocatalysts. The yields in highlycrystalline polymer, howwherein R R R or R represents hydrogen, alkyl,aryl, aralkyl, and cycloalkyl; and the aryl radicals may be substitutedwith nitro, alkyl, halogen, or alkoxy radicals, provided that when R Rand R =hydrogen, R; has at least three carbon atoms.

The alkyl group of the dialkylzinc may be for example, methyl, ethyl,propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, isopentyl ora higher hydrocarbon radical.

As a co-catalyst in the catalyst system it is preferred to use water,although alcohols and amines, especially secondary amines, areemployable.

It is preferred to use 0.4 to 1.2 mole of the co-catalyst per mole ofdialkylzinc. If more than 1.2 moles of cocatalyst are used per mole ofdialkylzinc, the yieldin polymer is strongly reduced.

The quantity of stabilizing agent per mole of dialkylzinc is lesscritical. A good yield may be obtained with 0.2 mole of stabilizingagent per mole of dialkylzinc. As

The stabilizing agent is a compound of the formula 3,579,480 PatentedMay 18, 1971 much as 3 or 4 moles of stabilizer per mole of dialkylzincmay also be used without difliculty.

A catalyst system comprising approximately equal numbers of moles ofdialkylzinc, of co-catalyst, and stabilizing agent is the simplest touse in practice and at the same time is highly efficient.

The quantity of dialkylzinc in the catalyst system lies customarilybetween 0.01 and 5 mole percent. It is preferred, however, that between0.1 to 1 mole percent dialkylzinc calculated on the aldehyde be used.

When the catalyst system is to be employed for polymerizingacetaldehyde, the yield in aldehyde polymer usually lies between 65 andpercent of the weight of the monomer used. The characteristic featuresof the use of the catalyst system are not only the high yield inpolymer, but also the stereoregularity and high molecular weight. Thepolymer therefore shows a high crystallinity. Crystallinity can beexpressed as a percentage of the total polymer which does not dissolvein methanol or acetone. In the system prepared according to theinvention, a crystallinity of and higher is generally found.

Because the system is oxygen-sensitive, it is preferred to employ anoxygen free atmosphere. Even if water is used as a co-catalyst, it isrecommended that the chemicals and vessels be carefully dried inadvance, because an excess of water will result in low yields.

In general, aldehyde polymerizations, such as that of acetaldehyde, arecarried out at low to very low temperatures. At ambient temperatures,there will be no reaction with acetaldehyde for example. Processing istherefore customarily carried out at minus 78 0, since this is a wellknown temperature which can be achieved and maintained with solidcarbonic acid and acetone. It is possible, however, to use temperaturesof minus 40 C.

When low-melting aldehydes such as acetaldehyde are employed, thecatalyst system may be utilized without resort to solvents. Thisprocedure is not ideal, because the quantity of free liquid decreases asthe polymerization progresses, and gives rise to the danger of aninhomogeneous reaction medium. It is therefore preferred that a solventbe used. Excess solvent is not harmful to the reaction, but isdisadvantageous. Aprotic and non-complexing solvents, which are liquidat the low temperatures required for polymerization, are preferred. Suchsolvents include toluene, pentane and hexane, As a rule from 2 to 20parts by volume of solvent per volume part of aldehyde may be usedwithout diificulty.

The three components of the catalyst system should be present togetherat the beginning of the polymerization. The simplest method of preparingthe catalyst system is to combine the three components in a solvent andto join the mixture with the aldehyde to be polymerized. It makes nodifference in results as to what succession is chosen to introduce thethree components into the solvent. It is therefore possible to bring thestabilizer into solution and then add the catalyst and co-catalyst.Other sequences are also employable.

If water is used as the co-catalyst and toluene as the solvent, thecatalyst system initially will be cloudy. It is possible to obtain ahomogeneous solution after a period of time has elapsed. In any event,the inhomogeneity will totally disappear when the aldehyde to bepolymerized has been added to the system. It is advantageous to stir thecatalyst system for several minutes, 5 minutes for example, prior toadding the aldehyde.

The catalyst system may be stored for an indefinite period of time.There is no noticeable decline in the yield when the catalyst system isemployed after an appreciable period of storage.

In the following examples three catalyst systems were prepared for use.

In catalyst system A, 1200 ml. of dry toluene and 20 mmoles oftetraphenylurea were introduced into a dry reaction vessel. The air wasreplaced by oxygen-free nitrogen. 20 mmoles of water and 20 mmoles ofdiethylzinc were introduced into the system while stirring.

The same results were reached with the catalyst systems B and C in thesame manner.

Table I shows the combined results of experiments that were carried outin the same manner, but with 20 mmoles of the stabilizer mentioned inthe table instead of the tetra- In catalyst system B, 1200 ml. of drytoluene and 20 phenylurea.

TABLE I (n)=normal Yi id in N0. R Ra Ra Ra pe rcent;

1 H H C2Hu 58 Q E Q 3 H H C cat-O- H --0H= 62 H H CH: 66

H H (n) CAHQ 72 Q Q Q CH3 CH3 011$ 71 H H CH; 70 H H H 0 H H CH2! 0 H HC2Hs 0 H H (n) CaH1 H E (11}0101121 22 H H C2Hs 70 H H (u)OmH21 78 CH2 HCH: 77 (11)O4HJ; H CH3 75 19 0 4 0 0 4 0 0 4 0 (I1)C4Hn 74 Cyclohexyl HH Cyelohexyl 69 22 O H H H 23 Naphthyl H H Naphthyl 70 mmoles ofdiethylzinc were introduced into a dry reaction vessel. The reactionvessel was freed of oxygen beforehand by employing dry-oxygen freenitrogen. 20 mmoles of water and 20 mmoles "of tetraphenylurea wereintroduced while stirring.

In catalyst system C, 1200 ml. of dry toluene, 20 mmoles of diethylzincand 20 mmoles of tetraphenylurea were introduced into a dry, nitrogenfilled reaction vessel followed by 20 mmoles of water.

EXAMPLE I The experiment was repeated with other stabilizers. This time,the catalyst system according to A contained 2 moles of stabilizer permole of diethylzinc and per mole of water. For the rest, the proportionsof the quantities were the same as for Table I.

CH3 (EH3 Instead of water, other co-catalysts may also be used, such asalcohols, amines and especially secondary amines.

In Table III a few additional data are mentioned.

TAB LE III Oo-catalyst Mmol Stabilizer Mmol Solvent Cm. Aldehyde4 molespercent Water 20 3 20 Toluene..- 1, 500 Propionaldehyda- 60 CHaOH. 20 320 do 1,500 Acetaldehyde 51 40 8 40 do 1, 500 Propionaldehyde" 58 30 1640 Hexane- 1 500 Acetaldehyde 80 30 2 30 Toluene.. 1,500 Butyraldehyde.50 Diphenylamin 30 17 Acetaldehydo 70 (n) ButylalcohoL 30 21 .do 72Phenol 30 23 Butyraldehyde 65 (n)Butylarnine 30 23 30 Toluene." 1 500Propionaldehyde 65 Water 20 19 40 .do 1,500 Aeetaldehyde. 70

1 Compound number.

N0'rn.In this table, ElIzZIl stands for diethylzinc, Pr Zn fordipropylzinc, l-BllzZIl for di-isobutylzinc, PentzZn for dipentylzincand i-Pent Zn for di-isopentylzinc.

In every instance the catalyst system of the invention performs in asuperior manner to those systems consisting simply of a single catalystand a stabilizer, a catalyst and a co-catalyst, or a catalyst alone.

In the catalyst system A, the quantity of water was halved to mmoles,and the final yield in polymer was 56%. When the amount of water wasreduced to 30 mmoles the yield dropped to 36%.

When alcohols are used as co-catalysts, the useful upper limit liesbelow 1 /2 moles of alcohol per mole of dialkylzinc. The lower limit isless critical and, as with water, a gradual decrease in the quantity ofalcohol will bring about a gradual decrease in the yield of polymer.

When secondary amines are employed, the upper limit is not critical,although the yield begins to drop at 2 moles of amine per mole ofdialkylzinc.

The stabilizers are interchangeable without significant alteration ofthe yield of polymer or the ease of processing.

The aldehyde to be polymerized may be any arbitrary polymerizablealiphatic saturated aldehyde such as acetaldehyde, propionaldehyde, orbutyraldehyde. Substituted aldehydes such as trichloroacetaldehyde ormixtures thereof may also be employed.

EXAMPLE II The catalyst system consisted of mmoles of dibutylzinc, 2Ommoles of water and 20 mmoles of tetramethylurea in 2000 mmoles of dryn-hexane. 3 moles of butyraldehyde were polymerized as according toExample I under moisture-free and oxygen-free conditions. Yield 60% ofcrystalline polymer calculated on the monomeric aldehyde brought toreaction.

EXAMPLE III The catalyst system consisted of 20 mmoles of dibutylzinc,25 mmoles of 1,3-diphenylurea and 20 mmoles of water in 2000 mmoles ofdry toluene. 3 moles of trichloroacetaldehyde as according to Example Iwere polymerized under moisture-free and oxygen-free conditions. Yieldin polymer 62%.

According to the present invention, the compounds which are used asstabilizers are those which have a catalytic influence on theinteraction between dialkylzinc and the co-catalyst, so that the activeagent is formed quickly. The stabilizer also has a stabilizing influenceon the active agent formed, so that the catalyst system is notinactivated.

We claim:

1. In a catalyst system for polymerizing saturated aliphatic aldehydeshaving at least two carbon atoms which includes the constituentsdialkylzinc and water as a cocatalyst, the improvement comprising theinclusion of a stabilizing agent in the catalyst system, said agentbeing selected from the group of compounds having the 20 formula R1\ Ill/Ra N-O-N R3 R4 25 wherein R R R and R are radicals selected from thegroup consisting of hydrogen, alkyl, cycloalkyl, aralkyl and substitutedand unsubstituted aryl radicals; said substituted aryl radicalscontaining substituents selected from the group consisting of nitro,alkyl, halogen, and alkoxy radicals; and when R R and R are hydrogen, R,has at least three carbon atoms, the water co-catalyst being present inan amount ranging from 0.4 to 1.2 moles per mole of dialkylzinc.

2. A catalyst system as set forth in claim 1, wherein the dialkylzinccompound is diethylzinc.

3. A catalyst system as set forth in claim 1, wherein a solvent isincluded in the catalyst system.

4. A catalyst system as set forth in claim 1, wherein approximatelyequal molar quantities of dialkylzinc, cocatalyst and stabilizing agentare employed.

5. A catalyst system as set forth in claim 1 wherein approximately 0.1to 1 mole percent of diakylzinc per mole of aldehyde is employed.

6. A catalyst system as set forth in claim 1, wherein the amount ofstabilizing agent present in the system is from 0.2 mole to 4 moles permole of dialkylzinc.

7. A catalyst system according to claim 1 wherein the saturatedaliphatic aldehyde is chlorine-substituted.

8. In the process for polymerizing saturated aliphatic aldehydes havingat least two carbon atoms with a catalyst system which includes theconstituents dialkylzinc and water as a co-catalyst, the improvementcomprising the steps of premixing the dialkylzinc and co-catalystconstituents with a stabilizing agent selected from the group consistingof compounds having the formula R, 0 R \N(%N/ wherein R R R and R areradicals selected from the group consisting of hydrogen, alkyl, aralkyl,cycloalkyl, and substituted and unsubstituted aryl radicals; saidsubstituted aryl radicals containing substituents selected from thegroup consisting of nitro, alkyl, halogen, and alkoxy radicals; and whenR R and R are hydrogen, R, has at least three carbon atoms, the waterco-catalyst being present in an amount ranging from 0.4 to 1.2 moles permole of dialkylzinc; and thereafter contacting the resulting catalyticmixture with the saturated aliphatic aldehyde in the absence of oxygenat a temperature below about 40 C.

9. A process as set forth in claim 8, wherein the catalyst system isformed in a solvent.

10. A process as set forth in claim 8, wherein the aldehyde isacetaldehyde.

11. A process according to claim 8 wherein the saturated aliphaticaldehyde is chlorine-substituted.

References Cited UNITED STATES PATENTS 8 7/ 1966 Grifiiths et a1.260--45.8 10/1967 Hagemeyer et a1. 26067 WILLIAM H. SHORT, PrimaryExaminer 5 L. M. PHYNES, Assistant Examiner US. Cl. X.R.

Patent No.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,579,480 DatedMay 18, 1971 It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Col. 3, line 72, "1000 should be 100 Col. 5, Table III, headings, "Yieldin Catalyst" should read Col. 5, Table III, fourth item in fourth column["Mmol"] Catalyst and "percent" should read Yield in should be 20 andCol. 6, line 42, [claim 5, line 2] "diakylzinc" should read (SEAL)dialkylzinc Signed and sealed this 28th day of December I 971 Attest:

EDWARD M.FLETCHER,JR. Attestinp: Officer ROBERT GOT'ISCHALK ActingCommissionerof Patents

